Camper -

Here are some excerpts from my book, "Data Analysis Using Microsoft Excel:
Updated for Office XP":

Left-Tail Test
p-value =IF(t<0,TDIST(ABS(t),df,1),1-TDIST(t,df,1))

Right-Tail Test
p-value =IF(t0,TDIST(t,df,1),1-TDIST(ABS(t),df,1))

Two-Tail Test
p-value =TDIST(ABS(t),df,2)

- Mike
www.mikemiddleton.com

"Camper" wrote in message
...
My question is how can I calculate a p-value for a negative t-value?

In several tests the t-test value is negative and I cannot use the
standard
TDIST(x,df,1) function. Is it correct to calculate the p-value of negative
t-values as:
1 - absolute(P[x])?

If the above is correct, is this the correct adaption to the TDIST
function:
=IF(x0,TDIST(x,deg_freedom,tails),(1-(TDIST(ABS(x),deg_freedom,tails))))

--
Mahalo for your help,
Camper